1. Field of the Invention
The present invention relates to an illumination apparatus and illumination method capable of emitting light at an object, and also relates to a measuring apparatus and measuring method capable of measuring a shape of the object, for example.
2. Description of Related Art
Conventionally, a non-contact optical probe is known which obtains position coordinates or the like of various portions of a measured object (work piece) by emitting laser light at the work piece and detecting the light reflected off a surface of the work piece (see, e.g., Japanese Publication of PCT International Application No. 2009-534969).
Examples of a non-contact optical probe include a line-type optical probe and a flying spot-type optical probe. In the line-type optical probe, laser light emitted from a laser light source is given a line shape by a beam expander or the like, then is fired at a work piece. A shape of the work piece is measured by capturing an image of the line-shaped light fired at the work piece.
The flying spot-type optical probe uses a reflecting mirror such as a galvano-mirror, provided so as to be capable of rotation. The laser light emitted from the laser light source strikes the reflecting mirror, then the point-shaped light (point laser) reflected by the reflecting mirror is launched (i.e., directed) at the work piece. At this point, the reflecting mirror is rotationally driven relative to the incident light and the point-shaped light scans over the work piece so as to trace a line shape in accordance with the rotational driving of the reflecting mirror. The shape of the work piece is measured by capturing an image of the point-shaped light scanning over the work piece.
In the flying spot-type measuring apparatus described above, the position (shape) of the work piece is calculated using principles of triangulation, based on the rotation angle of the reflecting mirror. Accordingly, in order to achieve high accuracy with the measuring apparatus, the issue of whether the rotation angle of the reflecting mirror is measured accurately is an important one.
For example, in order to detect the rotation angle of the reflecting mirror, a rotary encoder or the like could be attached to the motor rotationally driving the reflecting mirror. However, in such a case, the rotary encoder would add a load to the motor and high-speed scanning of the laser light over the work piece would become difficult. In addition, the motor would be larger due to a requirement for adequate rotational torque, and the measuring apparatus would be difficult to reduce in size.